﻿
function Secret_Key(str,pwd,type) {	
    var b = new Base64(); 
    if(type=='encryption'){

        str = b.encode(str);
        var prand = "";
        for(var i=0; i<pwd.length; i++) {
        prand += pwd.charCodeAt(i).toString();
        }
        var sPos = Math.floor(prand.length / 5);
        var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos*2) + prand.charAt(sPos*3) + prand.charAt(sPos*4) + prand.charAt(sPos*5));
        var incr = Math.ceil(pwd.length / 2);
        var modu = Math.pow(2, 31) - 1;
        if(mult < 2) {
        alert("Please choose a more complex or longer password.");
        return null;
        }
        var salt = Math.round(Math.random() * 1000000000) % 100000000;
        prand += salt;
        while(prand.length > 10) {
        prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();
        }
        prand = (mult * prand + incr) % modu;
        var enc_chr = "";
        var enc_str = "";
        for(var i=0; i<str.length; i++) {
        enc_chr = parseInt(str.charCodeAt(i) ^ Math.floor((prand / modu) * 255));
        if(enc_chr < 16) {
            enc_str += "0" + enc_chr.toString(16);
        } else enc_str += enc_chr.toString(16);
        prand = (mult * prand + incr) % modu;
        }
        salt = salt.toString(16);
        while(salt.length < 8)salt = "0" + salt;
        enc_str += salt;
        return enc_str;
    }

    if(type=='decryption'){
        var prand = "";
        for(var i=0; i<pwd.length; i++) {
            prand += pwd.charCodeAt(i).toString();
        }
        var sPos = Math.floor(prand.length / 5);
        var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos*2) + prand.charAt(sPos*3) + prand.charAt(sPos*4) + prand.charAt(sPos*5));
        var incr = Math.round(pwd.length / 2);
        var modu = Math.pow(2, 31) - 1;
        var salt = parseInt(str.substring(str.length - 8, str.length), 16);
        str = str.substring(0, str.length - 8);
        prand += salt;
        while(prand.length > 10) {
            prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();
        }
        prand = (mult * prand + incr) % modu;
        var enc_chr = "";
        var enc_str = "";
        for(var i=0; i<str.length; i+=2) {
            enc_chr = parseInt(parseInt(str.substring(i, i+2), 16) ^ Math.floor((prand / modu) * 255));
            enc_str += String.fromCharCode(enc_chr);
            prand = (mult * prand + incr) % modu;
        }

        return b.decode(enc_str);
    }
}

function Base64() {
    _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

    this.encode = function (input) {
        var output = "";
        var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
        var i = 0;
        input = _utf8_encode(input);
        while (i < input.length) {
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);
            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;
            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }
            output = output +
            _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
            _keyStr.charAt(enc3) + _keyStr.charAt(enc4);
        }
        return output;
    }

    this.decode = function (input) {
        var output = "";
        var chr1, chr2, chr3;
        var enc1, enc2, enc3, enc4;
        var i = 0;
        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
        while (i < input.length) {
            enc1 = _keyStr.indexOf(input.charAt(i++));
            enc2 = _keyStr.indexOf(input.charAt(i++));
            enc3 = _keyStr.indexOf(input.charAt(i++));
            enc4 = _keyStr.indexOf(input.charAt(i++));
            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;
            output = output + String.fromCharCode(chr1);
            if (enc3 != 64) {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64) {
                output = output + String.fromCharCode(chr3);
            }
        }
        output = _utf8_decode(output);
        return output;
    }
    _utf8_encode = function (string) {
        string = string.replace(/\r\n/g,"\n");
        var utftext = "";
        for (var n = 0; n < string.length; n++) {
            var c = string.charCodeAt(n);
            if (c < 128) {
                utftext += String.fromCharCode(c);
            } else if((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            } else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }

        }
        return utftext;
    }
    _utf8_decode = function (utftext) {
        var string = "";
        var i = 0;
        var c = c1 = c2 = 0;
        while ( i < utftext.length ) {
            c = utftext.charCodeAt(i);
            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            } else if((c > 191) && (c < 224)) {
                c2 = utftext.charCodeAt(i+1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            } else {
                c2 = utftext.charCodeAt(i+1);
                c3 = utftext.charCodeAt(i+2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }
        }
        return string;
    }
}
